(1) Field of the Invention
The present invention reaates to wave parameter measurement devices and more particularly to a device for determining real-time, ocean surface, sea-state conditions from a submersible platform operating at substantial depth.
(2) Description of the Prior Art
The unique problems associated with measurement of surface wave characteristics from beneath the ocean surface by a submerged submarine has received little attention to date. There is, however, great interest in measuring such surface wave conditions due to the profound effect that surface waves have, not only upon the decision to launch submarine missiles, but also upon potential destabilization of the launching submarine itself. During submarine at-sea exercises, missile failures have occurred which were later directly attributed to the adverse effects of extant surface wind and wave conditions. Such conditions exceeded missile design limits producing structural damage to missile control surfaces during buoyant ascent to the surface. The ensuing disruption of the underwater missile trajectory resulted in the missile's inability to achieve stable flight trajectory and hence in flight failure. Furthermore, it has been bserved that large surface waves can cause severe roll and pitch of the submarine itself which may also impede launch operations from shallower depths.
Due to these deleterious surface wave effects on both missile and launch platform, a principle criteria currently used to arrive at a submarine missile launch decision is the maximum sea-state design limit of the missile in relation to sea surface conditions present at time of launch. Surprisingly though, there is a general lack of agreement about, or even understanding, as to what this sea-state design limit means and specifically how it translates into dynamic effects on the weapon. More importantly, no objective and consistently reliable means of accurately measuring sea-state has been provided to submarines which are nevertheless required to launch sea state limited missiles. The submarine commander is left to make critical sea-state estimates using either or both of the only two methods presently available to him. These methods comprise either periscope observations of short duration made by the launching submarine or second party observation reports received via communications link. Periscope observations have disadvantages in that they require the submarine to be at near surface depth and also require a subjective "eyeball" estimate by an observer. At-sea exercises have repeatedly demonstrated the inaccuracies of such estimates. Second party reports also have serious disadvantages in that they not only require proximity of the submarine to the surface but also are generally not of a timely nature. These reports provide only recently observed conditions over a broad geographical area vice exact conditions present in the local operational area at the intended moment of launch. In addition, both of these methods adversely impact the tactical security of the submarine in requiring that it come to periscope depth thus providing an undesirable detection opportunity for an adversary.
To date, efforts to improve the ability of a deeply submerged submarine to remotely assess sea surface wave height conditions have been limited to the development of indirect acoustic monitoring techniques. These techniques seek to correlate wind created surface conditions with ambient acoustic noise levels generated by these surface conditions and received by onboard sonar systems, and ultimately with wave height. While this approach shows some promise, it will require collection of extensive amounts of acoustic data and it will be a long time, if ever, before thi approach yields results which can be routinely and consistently relied upon by operational fleet submarines.